Refrigerator defrosting device



REFRIGERATOR DEFROSTING DEVICE Filed Sept. .9, 1931 ZSheets-Sheet 1Inventor CM greet/er Jan. 22, 1935. c. w. GREEVER, JR 1,988,552

REFRIGERATOR DEFROSTING DEVICE Filed Sept. 9, 1931 Z-Sheets-Sheet 2MOTOR Invenlor 6. W greet er g 4mm Patented Jan. 22, 1935 UNITED STATESPATENT OFFICE This invention relates to a device'for defrostingmechanical refrigerators, and has for its primary obje t to provide, ina manner as hereinafter set forth, a device of this character emying anovel construction, combination, and arrangement of parts whereby theelectric motor of the mechanical refrigerator will be shut offperiodically for a length of time sufllcient to permit the temperatureto rise in the refrigerator and defrost the cooling unit.

Other objects of the invention are to provide a refrigerator defrostingdevice of the aforementioned character which will be simple inconstruction, strong, durable efficient and reliable in operation andwhich may be manufactured at low cost.

All of the foregoing and still further objects and advantages of theinvention will become apparent from a study of the followingspecification, taken in connection with the accompanying drawingswherein like characters of reference designate corresponding partsthroughout the several views, and wherein:

Figure 1 is a view in front elevation of a refrigerator equipped with adefrosting device in accordance with the present invention.

Figure 2 is a view in elevation of the device with the closure plate ofthe casing removed.

Figure 3 is a view of a modified form of the invention.

Referring now to the drawings in detail, it will be seen that thereference numeral 1 designates a conventional mechanical refrigeratorhaving therein a cooling unit 2. The reference numeral 3 designates acasing mounted on top of the refrigerator 1 and journalled for rotationin the casing is a horizontal shaft 4 having fixed thereon a large gear5.

The reference numeral 6 designates a clock 40 which may be ofconventional type which is disposed on the refrigerator 1 adjacent thecasing 3. The shaft 7 is journalled in the casing 3 and extendsoutwardly therefrom and is operatively connected to the clock 6 foractuation thereby. A comparatively small gear 8 is fixed on the shaft 7within the casing 3 and is constantly in mesh with the large gear fordriving same.

The reference numeral 9 designates generally a switch which isinterposed in the electric cir- 50 cult 10 to the electric motor (notshown) of the refrigerator 1. The switch 9 comprises a sta-, tionarycontact 11 and a movable contact 12 mounted on an intermediate portionof a flexible arm 13. A cam 14 is fixed on the shaft 4 and 55' isadapted for engagement with the free end portion of the arm 13 in amanner to disengage the contacts 11 and 12 with each complete revolutionof the shaft 4.

A bracket 15 is mounted in the casing 3 and is provided with an openingin which is operable the free end portion of a keeper 16 which ispivotally mounted on -the arm 13. -The keeper 16 is provided with a hookor lug 17 which is engageable with the bracket 15 for releasablysecuring the arm 13 in raised position for maintaining the switch 9 openafter the cam 14 passes the arm 13.

A spring 18 is connected with the free end portion of the keeper 16 foryieldingly urging said keeper into operative engagement with the bracket15.

Also mounted in the casing 3 is a bellows thermostat 19 having dependingtherefrom into the refrigerator l'adjacent the cooling unit 2 a thermaltube 20 having an enlargement 21 on its lower end. The reference numeral23 designates generally an electric switch which is mounted in thecasing 3 adjacent the bellows thermostat 19. The switch 23 comprises thestationary contact 24 and a movable contact 25 mounted on anintermediate portion of a flexible arm 26 which is operatively engagedwith the upper end of the bellows thermostat 19 for actuation thereby.

A coil spring 27 is operatively engaged with the arm 26 for yieldinglyurging said arm in a direction to open the switch 23. The tension of thecoil spring 27 may be regulated as desired through the medium of anadjusting screw 28 which is threadedly mounted in the casing 3 andoperatively engaged with the coil spring.

The reference numeral 29 designates an electro-magnet which is mountedin the casing 3 in a position to attract the keeper 16 thereto when saidmagnet is energized, thus swinging the keeper from its operative to itsinoperative position against the tension of the spring 18 and permittingthe switch 9 to close. a

An electric circuit 30 connects the electro-' magnet 29 with the motorcircuit 10 and the switch 23 is interposed-in said circuit 30.

In operation, the switch 9 is normally closed to permit the electriccurrent to pass through the motor of the refrigerator 1. The shaft 4 isdriven at the desired speed by the clock 6 to complete one revolution,for example, every ten days. At the completion of each revolution of theshaft 4, the cam 14 engages the arm 13 and opens the switch 9, therebyde-energizing the electric motor of the refrigerator 1.

v The cooling unit 2 of the refrigerator is thus rendered inoperativeand the temperature in said refrigerator slowly rises and defrosts thecooling-unit. As the temperature in the refrigerator rises, the bellowsthermostat 19 is, of course, expanded. As before stated, when the arm 13is raised by the cam 14 to open the switch 9, the keeper 16 is caused bythe spring 18 to engage the bracket 15 to secure said arm 13 in a raisedposition, thereby maintaining the switch 9 open. I

When the bellows thermostat 19 is expanded by the rising temperature inthe refrigerator 1 and consequently in the thermal tube 20 the switch 23is closed thereby energizing the electro-magnet 29. The energizedelectro-magnet 29 attracts the keeper 16 thereto as hereinbeforeexplained, thereby disengaging the hook or lug- 1'7 from the bracket 15and permitting the arm 13 to fall, thereby closing the switch 9.

The electric motor of the refrigerator 1 is thus again energized tofunction after the defrosting operation.

In the modified form of the invention illustrated in Figure 3 of thedrawings, electric switches designated generally by the referencenumerals 31 and 32 are interposed in the electric circuit 10 of theelectric motor of the refrigerator. The switch 31 comprises a resilient,

bifurcated stationary contact 33 and a movable blade contact 34, mountedon a pivoted lever 35 and engageable between the bifurcations of saidcontact 33 and frictionally retained thereby.

The switch 32 comprises a contact 36 mounted on an intermediate portionof a flexible arm 37 having its free end portion disposed beneath thefree end portion of the lever 35 for engagement therewith. Theswitch 32further includes a contact 38 engageable with the contact 36 and mountedon an intermediate portion of a flexible arm 39, the free end portion ofwhich is engaged with the upper end of the bellows thermostat 19 foractuation thereby.

In the operation of the modification shown in Figure 3 of the drawings,the switch 31 is normally closed. As the temperature in the refrigeratorrises, the bellows thermostat 19 expands and closes the switch 32, thusenergizing the motor of the refrigerator cooling unit. After the coolingunit has functioned for a suflicient length of time, the temperature inthe refrigerator, of course, drops, thereby causing the bellowsthermostat 19 to contract to open the switch 32 and deenergize themotor.

When it is desired to defrost the'cooling unit of the refrigerator, theswitch 31 is opened by manually actuating the hand lever 35 in amanner.to disengage the contact 34 from the contact 33. Thus, theelectric circuit to the motor of the refrigerator cooling unit has beenmanually opened, and the temperature in the refrigerator begins to rise.As the temperature rises, the bellows thermostat 19 is expanded and theswitch 32 is first closed. -However, the switch 31 is still open and,therefore, the motor circuit is also still open. After the switch 32 hasbeen closed, the temperatm'e'in the refrigerator continues to rise untilthe bellows thermostat 19 has been expanded sufficiently to close theswitch 31 through the medium of the arm 37 of the switch 32 which isengaged beneath the lever 35 of said switch 31. By this time, thecooling unit of the refrigerator will have been in-operative for asuilicient length of time to permit the temperature in the refrigeratorto rise suiiiciently to defrost said cooling unit. The switch 31 remainsclosed until it is again manually opened for defrosting the cooling unitof the refrigerator.

It is believed that the many advantages of a refrigerator defrostingdevice in accordance with the present invention will be readilyunderstood, and although the preferred embodiments of the invention areas illustrated and. described, it is to be understood that changes inthe details of construction and in the combination and arrangement ofparts may be resorted to which will fall within the scope of theinvention as claimed.

What is claimed as new is:

1. A defrosting device for mechanical refrigerators of the type having acooling unit and electric motor actuated means for operating the coolingunit, comprising, in combination, a switch interposed in the motorcircuit, and a thermally closed switch interposed in the motor circuitand operatively engageable with the first named switch for closing saidfirst named switch.

2. A defrosting device for mechanical refrig- I

